package com.jumper.terry.galleydemo;

import android.support.v4.view.ViewPager;
import android.view.View;

/**
 * Created by Terry on 2017/1/14 15:53.
 *
 * @author Terry
 * @version [版本号, YYYY-MM-DD]
 * @since [产品/模块版本]
 */

public class DepthPageTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = 0.75f;

    @Override
    public void transformPage(View view, float position) {
        int pageWidth = view.getWidth();
        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setAlpha(MIN_SCALE);
            view.setScaleX(MIN_SCALE);
            view.setScaleY(MIN_SCALE);
        } else if (position <= 0) { // [-1,0]
            // Use the default slide transition when moving to the left page

            //view.setAlpha(MIN_SCALE + (1 - MIN_SCALE) *(1 - Math.abs(position)));


            float scaleFactor = MIN_SCALE
                    + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);

//            view.setAlpha(1);
//            view.setTranslationX(0);
//            view.setScaleX(1);
//            view.setScaleY(1);
        } else if (position <= 1) { // (0,1]
            // Fade the page out.
            //view.setAlpha(MIN_SCALE + (1 - MIN_SCALE) *(1 - position));
            // Counteract the default slide transition


            //view.setTranslationX(pageWidth * -position);


            // Scale the page down (between MIN_SCALE and 1)
            float scaleFactor = MIN_SCALE
                    + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);
        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setAlpha(MIN_SCALE);
            view.setScaleX(MIN_SCALE);
            view.setScaleY(MIN_SCALE);
        }
    }
}
